Magnetic resonance force microscopy (MRFM) is an imaging technique that acquires magnetic resonance images (MRI) at nanometer scales, and possibly at atomic scales in the future. An MRFM system comprises a probe, method of applying a background magnetic field, electronics, and optics. The system measures variations in the resonant frequency of a cantilever or variations in the amplitude of an oscillating cantilever. The changes in the characteristic of the cantilever being monitored are indicative of the tomography of the sample. More specifically, as depicted in FIG. 1, an MRFM probe 100 comprises a base 102 with a cantilever 104 tipped with a magnetic (for example, Samarium cobalt) particle 106 to resonate as the spin of the electrons or nuclei in the sample 101 are reversed. There is a background magnetic field 108 generated by a background magnetic field generator 110 which creates a uniform background magnetic field in the sample 101. As the magnetic tip 106 moves close to the sample 101, the atoms' electrons or nuclear spins become attracted (force detection) to the tip and generate a small force on the cantilever 104. Using a radio frequency (RF) magnetic field applied by an RF antenna/wire coil 117 through the RF source 105, the spins are then repeatedly flipped at the cantilever's resonant frequency, causing the cantilever 104 to oscillate at its resonant frequency. In the geometry shown, springiness preservation by aligning magnetization (SPAM), when the cantilever 104 oscillates, the magnetic particle's 106 magnetic moment remains parallel to the background magnetic field 108, and thus it experiences no torque. The displacement of the cantilever is measured with an optical sensor 114 comprised of an interferometer (laser beam) 116 and an optical fiber 118 to create a series of 2-D images of the sample 101 held by sample stage 120, which are combined to generate a 3-D image. The interferometer measures the time dependent displacement of the cantilever 104. Smaller ferromagnetic particles and softer cantilevers increase the signal to noise ratio of the sensor. Current magnetic resonance force microscopy probes are limited to small samples due to probe geometries, where the radio frequency (RF) magnetic field is applied by a wire coil 117 positioned at an edge 120 of the sample 101. Because the wire coil 117 must be positioned at the edge 120 of the sample 101, the probe can only measure the topography near the edge or on a small sample.
Therefore, there is a need in the art for probe for magnetic resonance force microscopy in a more flexible manner for scanning arbitrarily large samples not limited to the edge of samples.